Fluorosis results from excessive ingestion of fluorides from all sources, such as water, food, and toothpaste. The Environmental Protection Agency has the regulatory task of establishing upper limits of fluoride in drinking water which are consistent with the public health, and has recently established higher limits (4.0 mg/l) than existed previously. The scientific basis for this decision, however, was not well developed. It is important to know if levels of fluorosis are changing over time, so that public policy on fluoride levels in drinking water can be monitored and adjusted, if necessary, from a basis of scientifically derived knowledge. The primary purpose of this project is to determine if the levels of fluorosis in lifelong-resident schoolchildren in a high fluoride community are the same as the levels of fluorosis in lifelong-resident adults. If fluorosis levels have not changes, this would suggest that amounts of fluoride ingested have not changed over the past several decades. If fluorosis levels have changed, in either direction, this result would suggest that policy should be re-examined. The study will be conducted in the community of Lordsburg, New Mexico, where the public water supply has contained approximately five times the optimal level of fluoride for the climate since the earliest measurements were made, and the water supply has been the same since the early part of this century. The data from the lifelong-resident adults have already been collected by the research team as part of an earlier study of fluorosis (NIDR contract no. DE 32443). Additional aims are to determine whether patterns of tooth-specific resistance to dental caries relative to fluorosis classification in the adults are also present in the children, and whether there is any age related trend in fluorosis severity, possibly related to enamel maturation, within the school age population. This is an application of epidemiology to assess public policy developed to protect the health of the American people.